Paleoproterozoic accretion and assembly of the Western Block of North China: A new model

This paper summarizes available lithostratigraphic, tectonothermal, geochronological and geophysical data to investigate the formation and evolution of the Yinshan Block, the tectonic nature of the Ordos Block, and the subduction to collision history of the Khondalite Belt, and establishes Paleoproterozoic accretion and assembly of the Western Block of the North China Craton. New critical evidence indicates that a magmatic arc developed in the Ordos Block caused by the initiation of northward slab subduction beneath the southern margin of the Ordos Block during 2.3-2.0 Ga, which contributed to the opening of the back-arc basin between the Ordos and Yinshan blocks. And then, the north margin of the Ordos Block was then transformed into a passive-type continental margin and collided with the Yinshan Block along the Khondalite Belt to form the Western Block after final closure of the back-arc basin during 1.97-1.91 Ga. Seismic data across the Western Block including a 300-km-long south-north-trending receiver function profile and a common conversion point stacking image in depth domain obviously show its crustal structure, in which the relics of two subduction slabs were preserved beneath the Ordos Block and the Khondalite Belt, respectively. Therefore, we propose a new tectonic model to help to better constrain Paleoproterozoic accretion and assembly of the Western Block in North China.

Automated summary

This study summarizes various data including lithostratigraphy, tectonothermal analysis, geochronology, and geophysics to investigate the formation and evolution of the Yinshan Block, the tectonic nature of the Ordos Block, and the subduction to collision history of the Khondalite Belt. New evidence suggests that a magmatic arc developed in the Ordos Block due to northward slab subduction, leading to the formation of a back-arc basin between the Ordos and Yinshan blocks. The collision between the passive-type continental margin of the north margin of the Ordos Block and the Yinshan Block along the Khondalite Belt resulted in the formation of the Western Block. Seismic data indicates the presence of subduction slabs beneath the Ordos Block and the Khondalite Belt, supporting a new tectonic model for the Paleoproterozoic accretion and assembly of the Western Block in North China.